The invention relates to apparatus for bonding portions of stacked paper sheets or the like to one another. More particularly, the invention relates to improvements in apparatus for applying adhesive paste to selected edge faces of successive stacks of overlapping sheets which consist of paper or other sheet material.
It is known to advance a succession of stacks of overlapping paper sheets along a predetermined path, to trim selected edge faces of successive stacks, to thereupon roughen the trimmed edge faces, and to ultimately apply adhesive paste to the trimmed and roughened edge faces so as to bond portions of neighboring sheets to one another and/or to allow for reliable application of flap-over covers or the like. The trimming action is performed by a driven circular knife which compacts the sheet portions adjacent the trimmed edge faces of stacks so that it is necessary to roughen the trimmed edge faces in order to ensure the application of requisite quantities of adhesive as well as sufficient penetration of adhesive into the adjacent portions of the sheets. As a rule, the means for roughening freshly trimmed edge faces of stacked sheets of paper comprises a driven milling tool which is installed at a discrete station between the trimming and adhesive applying stations with attendant increase in the bulk of the apparatus and additional cost for the milling cutter and means for journalling and driving the cutter. Moreover, the cutter removes minute articles of paper or other material which is used to make the sheets so that the apparatus and the surrounding area are contaminated unless the apparatus is equipped with complex, costly and energy-consuming dust collecting means. The dust cannot be readily recycled so that the corresponding percentage of the material of the stacks is lost.